Back in 2015 Google released developer preview of Android M ( Known as Android 6.0 Marshmallow now ) , Android M Developer preview came with Night Mode feature . But Google removed that feature from Official Android 6.0 Marshmallow .

But the feature will be back with Android N . Along with Dark theme , we can expect Multi-Window , No App drawer and other interesting features . Though Android N will look almost same as Android 6.0 Marshmallow and Lollipop in Interface ,